4. Game engine needs more improvement. (Sorry GGG. But it's the truth.) Eg: characters obscured by the environment too much; Dominus battle crawls on lower-spec'd machines, two-stage monsters need to be "re-targeted" after killing their first stage (eg, those sand-crab things) etc.
5. RNG makes me it's bitch too often.
6. Trading is BORING. But unfortunately, necessary. (Such tedium! Very yawn!)
7. Switching between weapon slots needs fixing: as it stands the second weapon slot is only good for leveling-up gems; if you swap between slots, the player needs to adjust their gem skills. This is *awful-bad-awful* and frankly, shoulda' been fixed in OB at the LATEST. Fixing weapon-slot switching would enable more diverse builds.

...having said all that, it's still the best ARPG game i've ever played...

Intellect is not a cure. Justice is dead. Fear, recrimination, innocence, sympathy, guilt, waste, failure, grief,
were things, emotions, that no one really felt anymore. Reflection is useless, the world is senseless. Evil is its only
permanence.

Best:
*The passive tree, gem system, and that its hard to reach max level
*The random loot (I have always hated static loot like in WoW)
*The nice non-p2w shop that a lot of f2p games fail to do

Worst:
*Desync
*Trade system (I love the currency system, but I just hate to trade.. dont know what they could do to fix this though :/, dont want AH, looking forward to trade patch)
*Cant think of anything else